Avalanche Forecast

Issued: Feb 6th, 2016 7:28AM

The alpine rating is considerable, the treeline rating is considerable, and the below treeline rating is moderate. Known problems include Wind Slabs and Persistent Slabs.

pgoddard, Avalanche Canada

Purcells.

Wind slabs, cornice fall, or a person could trigger a deeply buried weak layer, creating a surprisingly large avalanche.

Summary

Confidence

Moderate - Timing or intensity of solar radiation is uncertain

Weather Forecast

A building ridge is expected to bring mainly sunny skies with no precipitation for the next three days. A warm southerly flow causes the freezing level to rise as high as 3000 m.For more details check out http://www.avalanche.ca/weather.

Avalanche Summary

We continue to receive reports of natural and skier triggered size 1-2 wind slabs from across the region. The January surface hoar layer remains a major concern, especially in the north Purcells where it has been responsible for several recent large avalanches. On Friday, a snow cat triggered a size 2 persistent slab on a SE aspect near 2300 m. Last Saturday, a size 3 sledder-triggered avalanche occurred in the Gorman Creek riding area near Golden. Around the same time, a size 3.5 skier-triggered persistent slab avalanche occurred a few drainages to the south of Gorman Creek on a north-facing alpine slope. Forecast warming may increase the reactivity of the persistent slab.

Snowpack Summary

Reactive wind slabs exist in the lee of ridges and terrain breaks at alpine and treeline elevations. These may be found lower in the start zones than normal due to the high wind speed. A persistent weak layer of surface hoar and facets buried in early January is now typically down 40-90 cm. The layer is slowly getting harder to trigger in many areas. However, reports of whumpfing and some recent large to very large avalanches around Golden indicate this layer is still very much a concern, especially in the north of the region. In general, the lower snowpack below this layer is well settled and strong.

Problems

Wind Slabs

Very strong winds have created wind slabs which may be further down the slope than normal. Watch for areas of cross-loading too.

Pay attention to overhead hazards like cornices.>Travel on ridges to avoid freshly wind loaded features. >

Aspects: North, North East, East, South East, South.

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 3

Persistent Slabs

The persistent slab problem demands respect, especially in the north of the region. Riders have triggered a couple of very large avalanches this week. Forecast warming could increase the sensitivity of this problem.

Be aware of the potential for remote triggers and wide propagations due to a layer of buried surface hoar and facets. >Be cautious around open slopes and convex rolls at and below treeline where buried surface hoar may be preserved. Big alpine features are also suspect.>Minimize exposure to sun exposed slopes when the solar radiation is strong.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible

Expected Size

3 - 5

Valid until: Feb 7th, 2016 2:00PM